Express your answer as a mixed number simplified to lowest terms. $19\dfrac{6}{7}-3\dfrac{4}{7} = {?}$
Explanation: Separate the whole numbers from the fractional parts: $= {19} + {\dfrac{6}{7}} - {3} - {\dfrac{4}{7}}$ Bring the whole numbers together and the fractions together: $= {19} - {3} + {\dfrac{6}{7}} - {\dfrac{4}{7}}$ Subtract the whole numbers: $=16 + {\dfrac{6}{7}} - {\dfrac{4}{7}}$ Subtract the fractions: $= 16+\dfrac{2}{7}$ Combine the whole and fractional parts into a mixed number: $= 16\dfrac{2}{7}$